1. Field of the Invention
The present disclosure relates to a water treatment membrane having high chlorine resistance and high permeability and a method of manufacturing the same, and more particularly, a water treatment membrane having superior chlorine resistance and permeability by including a fluorine compound in a polyamide layer and a method of manufacturing the same.
2. Description of the Related Art
An osmosis phenomenon refers to a phenomenon in which a solvent moves from a solution having a low solute concentration to another solution having a high solute concentration by passing through a semipermeable separation membrane isolating the two solutions. In this case, pressure acting on the solution having a high solute concentration through the movement of the solvent refers to osmotic pressure. However, when external pressure having a level higher than that of osmotic pressure is applied, the solvent moves towards the solution having a low solute concentration, and such a phenomenon is known as reverse osmosis. Various types of salt or organic material may be separated by a semipermeable membrane using a pressure gradient as driving force, according to the principle of reverse osmosis. A water treatment membrane using a reverse osmosis phenomenon has been used to separate a molecular-level material, remove salts from salt water or sea water and supply water for domestic, commercial and industrial purposes.
The water treatment membrane may representatively be a polyamide-based water treatment membrane, by way of example. The polyamide-based water treatment membrane is manufactured by a method of forming a polyamide active layer on a microporous layer support. More particularly, the polyamide-based water treatment membrane is prepared by forming a polysulfone layer on a non-woven fabric to form a microporous support, dipping the microporous support in an aqueous m-phenylene diamine (mPD) solution to form an mPD layer, and dipping the mPD layer in an organic trimesoyl chloride (TMC) solvent to allow the mPD layer to be brought into contact with the TMC so as to be interfacially polymerized to thereby form a polyamide layer.
Meanwhile, such a water treatment membrane needs to satisfy several conditions so as to be used for commercial purposes, and one of the conditions is a high salt rejection rate. A commercially required salt rejection rate of the water treatment membrane may be at least 97% or more in brackish water. Another crucial property of the water treatment membrane may be a capability of allowing a relatively large amount of water to penetrate therethrough at a relatively low pressure, that is, a high permeate flux. In general, a membrane permeate flux may be 10 gallon/ft2-day (gfd) at a pressure of 800 psi in seawater, and may be 15 gfd or more at a pressure of 220 psi in salt water. However, since an oppositional relationship may exist between the salt rejection rate and the permeate flux properties, the manufacturing of a water treatment membrane having a superior salt rejection rate as well as a high permeate flux may be infeasible in practice.
In addition, in the case of the polyamide-based water treatment membrane, when the membrane is exposed to a chlorine radical, the salt rejection rate may be sharply deteriorated while a polyamide combination is dissolved. Thus, there is demand for a polyamide-based water treatment membrane to prevent a degradation in performance of a product and to have high chlorine resistance for improvements in a life cycle thereof. To this end, a method of forming a coating layer containing a fluorine compound having superior chlorine resistance on a polyamide layer has been suggested. However, in such a method, since a separate process needs to be undertaken to form the coating layer, the number of processes may be increased and due to the formation of the coating layer, the permeate flux of the polyamide layer may be lowered.